1. Field of the Invention
The present invention relates to rotating magnetic disk drives, and more particularly, to a disk drive having a servo control system optimized for faster determination of repeatable runout correction values.
2. Description of the Prior Art and Related Information
In order to remain competitive, disk drive manufacturers must continually provide increased data storage capacity while rigidly controlling disk drive manufacturing cost. One key to increased storage capacity is increased track density, often expressed as tracks per inch or TPI. A limiting factor on the track density is repeatable runout (RRO) which results from imperfections, with respect to a perfect circle, in the location of servo information along a track on a disk surface in the disk drive. The RRO imperfections are relatively static over time and the effect of the RRO may be attenuated by measuring the RRO during manufacturing and using the RRO measurements in a head-position servo loop to compensate for the RRO.
Accordingly, there exists a need for a technique for more efficiently determining RRO cancellation values.